/*
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.dspl.validate.violation;

import com.google.common.collect.Ordering;
import com.google.dspl.validate.violation.Violation.Severity;

/**
 * @author James Grimm
 */
public final class ViolationOrderings {

  private static final class SeverityOrdering extends Ordering<Violation> {

    @Override
    public int compare(Violation arg0, Violation arg1) {
      int severityIndex0 = computeSeverityIndex(arg0.getSeverity());
      int severityIndex1 = computeSeverityIndex(arg1.getSeverity());
      return severityIndex0 - severityIndex1;
    }

    private int computeSeverityIndex(Severity severity) {
      switch (severity) {
        case CRITICAL:
          return 0;
        case ERROR:
          return 1;
        case WARNING:
          return 2;
        default:
          throw new AssertionError("Unknown severity " + severity);
      }
    }
  }

  public static Ordering<Violation> bySeverity() {
    return new SeverityOrdering();
  }

  private ViolationOrderings() {
    throw new AssertionError("Do not instantiate");
  }
}
